Liquid hydrocarbons, including many oil feedstocks, often contain difficult to remove sulfur in the form of organosulfur compounds as well as metals and other heteroatom-containing compounds that hinder usage of the hydrocarbons. Sulfur can cause air pollution, and can poison catalysts used in petroleum processing or catalysts designed to remove hydrocarbons and nitrogen oxide from motor vehicle exhaust. There has been a worldwide trend to limit the amount of sulfur in hydrocarbon fuels, such as gasoline, diesel, and fuel oils, including marine bunker fuels. Metals contained in the hydrocarbon stream can also poison catalysts typically utilized for removal of sulfur through standard and improved hydro-desulfurization processes whereby hydrogen reacts under extreme conditions to break down the sulfur bearing organosulfur molecules.
Sodium has been recognized as potentially effective for the treatment of high-sulfur hydrocarbons, including petroleum oil distillate, crude, heavy oil, bitumen, and shale oil. Sodium is capable of reacting with the oil and its contaminants to dramatically reduce the sulfur, nitrogen, oxygen, and metal content through the formation of sodium sulfide compounds (sulfide, polysulfide and hydrosulfide) as well as other byproducts. However, removal of these byproducts from the treated feedstock can be challenging. The suspensions and/or emulsions the byproducts may form often cannot be completely removed using standard separation techniques, and can be difficult to carry out efficiently on an industrial scale. Indeed, no large scale desulfurization using sodium metal or other alkali metals is in regular commercial use due in part to this problem.